The art of the production of food-grade dough is replete with different types and classifications of inventions dealing with dough production including simple techniques to relatively sophisticated procedures. However, the production of pretzel dough, or other yeast levened dough, as nearly as can be determined, has heretofore been accomplished by batch-type processes or operations, as opposed to a continuous dough production process.
Batch-type pretzel manufacturing is subject to inefficiencies which lead to inconsistent quality in the final product. The inefficiencies arise when a batch or quantity of raw ingredients are mixed into a dough. In commercial operations it is desirable to mix a large quantity of dough. This dough is then extruded into a pretzel shape and further processed. The time lapse between the extrusion of the initial portion of the dough to the last portion of the dough in a particular batch causes differences in the aging of the dough.
The differences and variations within a batch of dough are a result of a significant problem of gluten formation in batch operations. For example, if a pretzel dough in a batch prepared process is permitted to sit prior to submersion in the sodium hydroxide bath, it develops a substantial gluten structure which results in a brittle pretzel. In a batch operation, a large amount of dough is produced at one time. Once the dough is produced it is shaped by extrusion and then immersed or soaked into the sodium hydroxide bath. The portion of the batch, which is extruded last, is aged and can well result in a brittle product due to substantial gluten development. Texture variations due to aging are also noticeable in the surface of the final product. Instead of a shiny, "glassy" appearance, the pretzel surface will have a cracked or "shattered glass" appearance. A cracked surface causes more rapid staling and reduces the shelf life of the product.
When aging differences from large batch operations for making pretzels are eliminated by producing numerous smaller batches of pretzel dough, variances between batches can exist. This also causes inefficiencies in the amount of time, equipment, and man hours required to constantly have a batch of dough mixed and prepared for extrusion and finalization of the product.
In commercial operations finishing of the product after the pretzel dough has been prepared by a batch operation includes taking a small piece of dough and then extruding and rolling it into a desired length. It is then twisted and dropped onto an elongated belt. The dough is passed through a specially prepared hot caustic solution which gives it a golden brown color and shiny finish. Salt is then dropped on the pretzel and it is passed through an oven. By the time it comes out of the oven the pretzel is completely baked. The baked pretzel is then allowed to dry to complete the extraction of as much moisture as possible. The pretzel is then ready for packaging.
There are many variations on this basic procedure, some directed to pretzel products and others to related snack-type products. For instance, in U.S. Pat. No. 3,876,815, a process for preparing a soft pretzel is disclosed, which includes the steps of mixing vinegar with pretzel dough prior to shaping the dough into the desired pretzel shape. The shaped dough is then refrigerated for about 30 minutes at 32.degree. F. and thereafter dipped into a caustic solution, such as sodium hydroxide, to obtain the desired color and finish. The dipped dough is then baked at about 550.degree. F. for about 7 minutes, during which time maximum expansion of the dough is achieved.
In U.S. Pat. No. 3,976,791 a process is disclosed for producing a pretzel product which, upon cooking, remains soft for an extended period of time, typically greater than twelve hours. The process involves preparing a dough comprising by weight, 51 parts water, 100 parts flour, and sufficient yeast to cause the dough to rise. The dough is then formed into the shape of a pretzel. The surface of the formed pretzel is then saturated with sodium hydroxide solution and thereafter cooled to a temperature below -15.degree. F. for at least one hour.
Further prior art teachings pertaining to the art of pretzel manufacture are contained in Matz, Cookie and Cracker Technology, AVI Publishing Company, Inc. (1968), at page 147, which is incorporated herein by reference.
One prior art teaching, namely U.S. Pat. No. 3,384,494 is stated to relate to the preparation of a dry, free-flowing pastry crust mix prepared on a continuous or semi-continuous basis. This patent teaches a batch-fed mixing apparatus which can be operated continuously or semi-continuously. The product that is produced by this patent is a dry free-flowing mixture of basically two ingredients, flour and shortening. The process claimed to produce this pastry crust mix, involves temperature criteria and mixing variations not required in the production of pretzels.